Embodiments of the present specification relate generally to power converters, and more particularly for controlling an instantaneous current in the power converters.
Typically, a power converter is employed to interface a power source to one or more electric loads. Also, the power converter is used to control flow of power from the power source to the one or more electric loads. Typically, the power converter includes solid state switches that are used to rapidly and/or intermittently interrupt or commutate an input current from the power source so as to effectuate conversion of the input current to an output current having different amplitudes and/or frequencies at the one or more electric loads. In one example, the power converter may be a direct current (DC) power converter that produces an output power at a substantially constant output voltage and/or current.
Furthermore, power conversion is a dynamic process that calls for rapidly sequenced changes in the state of the solid state switches in the power converter to interrupt or commutate the input current from the power source to the electric loads. Although the solid state switches exhibit high conduction or resistance in corresponding closed or open steady states, the solid state switches typically exhibit capacitive and resistive switching losses during a transition between the states. Also, at higher switching frequencies of the power converter, parasitic elements, such as leakage inductance of a transformer and parasitic inductance of a cable may become more dominant, and hence may result in higher switching losses in the power converter.
Conventionally, the power flow is controlled by adjusting the phase shift between a primary side voltage and a secondary side voltage of the power converter. This phase shift control technique is simple to implement and allows a large operating range. However, this phase shift control technique can drive large currents inside the converter components when a voltage ratio is substantially different from a transformer ratio of the power converter. These large currents in turn result in higher conduction and switching losses in the solid state switches. Also, the current may exceed the maximum current capability of the components in the power converter, thereby resulting in damage to the components in the power converter.